In air handling and ventilating equipment, louvers are used to permit air flow into or out of a building while preventing the elements from entering the building through the opening for the air. Conventionally, louvers come in fixed sizes to fit in fixed-sized openings. Conventional louvers range from relatively small sizes, in the neighborhood of 18 inches in height, up to 48 inches in height, with similar ranges in width.
The variety of sizes of louvers conventionally used and specified by architects for buildings makes it necessary for louver manufacturers and distributors to manufacture and stock a wide range of sizes of louvers. This is expensive.
Additionally, while professional builders, carpenters and the like may have no difficulty installing a given-size louver in a given-size opening, homeowners and other do-it-yourselfers may have difficulty making an orifice the exact width required to receive a given louver.
The necessity for distributors to carry a wide range of louver sizes reduces distributor responsiveness to orders. If the distributor does not have the size louver proper in stock, the distributor cannot respond to a given order in a timely fashion.